7 letters · 9 points in Scrabble
noun a rester who is sleeping
noun a spy or saboteur or terrorist planted in an enemy country who lives there as a law-abiding citizen until activated by a prearranged signal
noun an unexpected achiever of success
originCompare Norwegian sleip (“a sleeper (a timber); as adjective, slippery, smooth”). See slape.
Etymology from Wiktionary, CC BY-SA 3.0